title: Energy expenditure, cardiorespiratory, and perceptual responses to shallow-water aquatic exercise in young adult women.
abstract: BACKGROUND
  Aquatic exercise (AE) is a popular form of physical activity, yet few studies have assessed the individual's energy expenditure (EE) associated with a continuous bout of AE. Studies using indirect calorimetry to measure EE have reported limitations associated with test methodology and the ability to control individual's exercise intensity or tempo.
  
  
  OBJECTIVE
  To evaluate EE and cardiorespiratory (CR) responses during a 40-minute shallow-water AE session in young adult women.
  
  
  METHODS
  Twenty-one healthy women (aged 21.7 ± 3.4 years) completed an orientation practice session and a 40-minute shallow-water AE session using a traditional exercise class format and the SWEAT video-based instructional cuing program. The high-intensity interval format included the following segments: 1) warm-up (3 minutes); 2) CR segment ( 22 minutes); 3) muscular endurance segment (ME; 10 minutes); and 4) cool-down (5 minutes). Subject oxygen consumption (VO2; mL/kg/min), heart rate (HR) and OMNI overall ratings of perceived exertion (RPE-O) were assessed each minute. Average kcal/min1, metabolic equivalents (METs; 1 MET = 3.5 mL/kg/min), and total kcals per segment and for the overall session were calculated.
  
  
  RESULTS
  The total subject EE throughout the 40-minute trial (including warm-up and cool-down segments) was 264 kcals, with an overall average of 6.3 kcals/min (5.6 METs).The average kcals/min expended throughout CR segments 2 through 6 was 8.05 (7.1 METs), with the Hoverjog segment producing the greatest average kcals/min at 8.3 (7.3 METs). The CR portion (22 min) contributed 65% of the total EE (171 kcals) of the 40-minute AE trial. For the overall AE trial, the highest and average subject VO2 achieved were 33.3 and 19.7 mL/kg/min, respectively. The average highest subject heart rate achieved was 177 beats per minute (bpm), equivalent to 90% of the participant's age-predicted HRmax.
  
  
  CONCLUSIONS
  Energy expenditure during a 40-minute AE session met national recommendations for a daily moderate-to-vigorous bout of physical activity offering a viable alternative to land-based exercise. Because AE serves as a partial-weight bearing modality, future studies are needed to clarify the EE of shallow-water AE in apparently healthy and clinical populations.
authors.affiliation: Assistant Professor, Department of Health and Physical Activity, University of Pittsburgh, Pittsburgh, PA. nagle@pitt.edu.
authors.forename: Elizabeth F
authors.initials: EF
authors.lastname: Nagle
authors.forename: Mary E
authors.initials: ME
authors.lastname: Sanders
authors.forename: Alex
authors.initials: A
authors.lastname: Shafer
authors.forename: Bethany
authors.initials: B
authors.lastname: Barone Gibbs
authors.forename: Jacquelyn A
authors.initials: JA
authors.lastname: Nagle
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Deldin
authors.forename: Barry A
authors.initials: BA
authors.lastname: Franklin
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Robertson
mesh_terms: D000293:Adolescent; D000328:Adult; D002153:Calorimetry, Indirect; D003430:Cross-Sectional Studies; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D013550:Swimming / Q000502:physiology*; D055815:Young Adult